1. Technical Field
The present invention relates generally to methods and apparatus for pelletizing lipids--such, for example, as animal and/or vegetable based fats, oils and greases--to form essentially "dry", discrete, integral lipid particles or pellets that may readily contain any desired percentage of pure, or essentially pure, lipids ranging up to, and in some instances in excess of, from 95% to 99% lipid materials less water of hydration; yet which are "dry", firm, solid, and easily handled--i.e., they do not bleed or otherwise exude lipids in liquid form and, consequently, do not exhibit an "oily" feel; are characterized by their stability and which are not subject to rancidity; and, which can, therefore, be readily mixed in any desired proportions with other feed products for animal consumption by, for example, ruminants, fowl, birds, fish, swine, canine and feline pets, etc.
More specifically, the invention permits the formation of discrete, "dry", solid pellets and/or particles of such lipids as: (i) rendered and unrendered materials; (ii) processed or unprocessed restaurant grease--i.e., yellow grease comprised of animal fats, vegetable oils, and/or mixtures thereof; (iii) bleachable fancy tallow; (iv) hydrogenated beef tallow; (v) "special" tallow; etc., which, while they may contain from 0%, or slightly more than 0%, to 30% or more moisture, exclusive of water of hydration, are integral or solid throughout their entire structure, are pourable and free-flowing, and exhibit the external characteristics of dryness and firmness that permit such pellets or particles to be easily handled from the point of origin thereof to a point of use, and to then be incorporated in any desired proportion with animal feed rations, range blocks, or the like without risk of rancidity, clumping, agglomeration or other non-uniform distribution because of the firm, "dry"--i.e., non-oily or non-greasy--surface texture of the pellet or particle. The pellets or particles are essentially temperature insensitive--i.e., they will not readily melt nor are they damaged by freezing, although excessive heat or cold does tend to reduce the moisture content--and, they may be formed in virtually any desired shape. Moreover, because the pellets or particles comprise lipids in integral dry form throughout the entire pellet or particle structure, they may be readily admixed with feed grains without being warmed; and, then pelletized in conventional feed mills to form solid pelletized animal feed rations containing up to on the order of 15%, or more, lipids.
In its more detailed aspects, the invention readily permits the incorporation of a wide range of optional additives with the lipid materials without affecting the pelletization process and/or the foregoing characteristics of resulting pelletized products such, merely by way of example, as: mineral supplements; nutrients; vitamins; medicants including antibiotics and/or antifungals; antioxidants; preservatives; etc. In a modified form of the invention, the pelletized lipids can readily serve as biodegradable controlled-time-release carriers for: pesticides--e.g., attractants or repellants which may be formed as pest control scatters; herbicides; fertilizers; hormones and/or growth nutrients; dust control scatters; deodorants; etc.
2. Background Art
The value of fats, oils (other than essential oils), and greases (other than hydrocarbon and/or petroleum based materials), herein generically referred to as lipids, as a nutritional feed supplement for virtually the entire gamut of the animal world including ruminants, swine, fowl, canine or feline pets, fish, birds, etc., has long been recognized. Unfortunately, however, the very nature of such lipids, which are commonly in liquid form or which exude or bleed liquified oil and/or grease exudates, particularly at elevated temperatures, has served to minimize their mass distribution and/or use as a feed supplement. Thus, the tendency of lipids to become rancid and spoil when subjected to oxidants serves to impose severe limitations on the shelf life of dry feed products incorporating such lipids. Moreover, lipid materials, when admixed with grain and similar dry feed products, are not only subject to rancidity but, in addition, they are temperature sensitive, tend to clump or otherwise agglomerate, and to disperse non-uniformly through such conventional feed products; and, consequently, they create severe packaging and handling problems. A typical, but not exclusive, problem area has been the inability to incorporate lipids as a nutritional feed supplement for range fed ruminants because, for example, efforts to incorporate lipids in any meaningful amounts in range blocks have been unsuccessful since the lipid materials tend to bleed out of the range block and to thereafter be subjected to oxidation, rancidity and spoilage, thus destroying the nutritive value of the remaining range block ingredients, rendering the range blocks difficult to handle and, indeed, often causing the range blocks to become soft and pliable, and to collapse or otherwise disintegrate.
Prior to the advent of the present invention, the foregoing problems have continued to plague the industry despite extensive expenditures of time and money in attempts to resolve the problems and to provide a system suitable for widespread mass distribution of lipid-type food supplements. Research directed to attempts to provide solutions to the problems has been conducted and/or sponsored by a wide range of institutions including, for example, the Fats And Proteins Research Foundation, Inc. of Des Plains, Illinois, as well as at innumerable university based research facilities, principally in the agricultural fields. For example, it has been known for years that lipids can be absorbed in a wide variety of edible absorbant host carriers or support matrices such as rice, puffed rice or wheat, wheat middlings, wheat bran, beet pulp, alfalfa meal, corn cobs, bees wings, edible clays or earths, etc. See, for example: Robison, U.S. Pat. No. 1,997,083 (oil treated bird seeds and other cereal products); Clayton, U.S. Pat. No. 2,991,178 (oil treated beans and seeds); Lewis, U.S. Pat. No. 3,257,209 (soybean oil meal); Pruckner et al, U.S. Pat. No. 3,340,065 (fat containing edible bleaching earth); and, Hoffman, U.S. Pat. No. 3,620,755 (soybean meal impregnated with edible oleaginous materials and cooked in boiling water). Unfortunately, the foregoing approaches, and many similar approaches contemplating the impregnation of an edible host carrier, have not met with acceptance or widespread commercial usage for a wide variety of reasons. For example, the host carrier itself renders the product suitable for use on a highly limited species-specific basis. The problems of stability, rancidity, temperature sensitivity, and mess in handling resulting from exudates, remain. The carrier itself often comprises substantially in excess of 50% of the weight and bulk of the thus treated feed product, not only limiting the amount of nutritional lipid values that can be fed to various types of animals but, also, significantly increasing the cost of distribution. The resulting impregnated carriers often have wet or oily surface coatings and are generally not free-flowing. Moreover, many of such carriers--for example, rice--are simply too expansive to permit widespread usage as animal feeds.
Another approach has involved relatively expensive and highly complex processes for converting fat or similar lipids to powdered dry form. Typical of this approach are the systems disclosed in Campbell, Jr. et al, U.S. Pat. No. 3,514,297, Grolitsch, U.S. Pat. No. 3,892,880, and Nappen, U.S. Pat. No. 4,232,052. However, such powdered lipid products are prohibitively expensive for use as an animal food supplement.
In the mid-1970's, the widespread research and experimentation then underway led to the purported "solution" disclosed in Scott et al, U.S. Pat. No. 3,925,560 and in Rawlings et al, U.S. Pat. No. 4,042,718. Thus, in these patents, the patentees disclose systems wherein lipids are encapsulated in protective protein-aldehyde complex coatings to produce concentrated high fat, dried, particulate, free-flowing compositions. While the efforts of Scott et al and Rawlings et al, for the first and only time prior to the advent of the present invention, produced "dry pellets" or particles characterized by a high lipid content which were contemplated as having utility for animal feed products, unfortunately the systems have met with no commercial acceptance because, if for no other reason, the aldehyde constituent was, and is, a known carcinogen and, consequently, the resulting product was not, and cannot be, approved for use as an animal feed supplement.
In U.S. Pat. No. 4,216,234, Rawlings et al disclose a particulate composition formed by a dispersion or emulsion of globules of nutrient lipids within an aqueous albumin containing medium which is thereafter formed into a gel and dried to form the composition--an arrangement characterized by a relatively low percentage of lipid content within the particulate product. In U.S. Pat. No. 4,217,370, Rawlings et al disclose a process for making lipid-containing foodstuffs comprising solublizing particulate proteinaceous matter, admixing a lipid material so as to form an emulsion, and contacting the emulsion with an effective amount of a pH adjusting agent to lower the pH to its isolectric point, thereby aggregating the protein and simultaneously microencapsulating the lipid. Again, the fat content of the resulting product tends to be relatively low. Moreover, both approaches are technically complex from a production standpoint, prohibitively expensive, present severe potential bacterial problems and, indeed, can result in products having carcinogenic properties.
Many prior art patents can be found which relate in general to the formation of gelatinous food products by the interaction of alginates with various metal salts and, particularly, with salts of calcium such as calcium carbonate. Typical of these patents are: Steiner, U.S. Pat. No. 2,441,729; Gibsen, U.S. Pat. No. 2,918,375; Freedman, U.S. Pat. No. 3,349,079; and, Miller et al, U.S. Pat. No. 3,455,701. In general, these patents disclose relatively slow gelation processes which generally require on the order of ten minutes for the calcium solution to cause the alginate to form a soft gel. A similar disclosure appears in an article authored by T. R. Andrew and W. C. MacLeod, Application And Control Of The Algin-Calcium Reaction, FOOD PRODUCT DEVELOPMENT, August-September 1970, at pp. 99, 101, 102 and 104. In this article, the authors discuss the formation of various types of artificial food products using a sodium alginate solution which can be slowly gelled by dispersion in an aqueous calcium salt solution or which can be instantaneously gelled by dispersion into a 10% solution of calcium chloride. It is stated that a mixture of an algin syrup with sugar, colorings, flavors, etc., can be deposited in a calcium chloride bath " . . . to form spheres which look like fruit or vegetable pieces . . . " or " . . . caviar . . . " (p. 104). None of the foregoing relate, however, to systems intended for or capable of pelletizing lipids.
In Peschardt, U.S. Pat. No. 2,403,547, the patentee proposes forming a viscous solution comprising 100 parts by weight of water, 20 parts by weight of glucose, and sodium alginate comprising from 1% to 2% by weight of the final solution, to which any desired optional colorings or flavorings may be added. To make spheroidal-shaped objects such as "cherries", the patentee proposes extrusion of the foregoing basic stock as "detached blobs" from extrusion nozzles into an aqueous solution of calcium chloride which is stated can range from " . . . as little as 1% or 3% or as much as 10% or more calcium chloride in the setting bath . . . " (Col. 2, 11. 44-46). Peschardt further suggests that shapes and forms other than spheroidal can be obtained by charging the basic alginate stock into mold recesses, and then depositing the pre-molded shapes of viscous stock into the setting bath. There is no teaching in Peschardt of the use of lipid ingredients.
Although the use of algin-like coagulants to form dry, stable, discrete, solid pellets or particles containing high concentrations of lipids has not heretofore been contemplated, it has long been recognized that algins are suitable for use as barrier layers in forming gel-like lipid emulsions that can be utilized as a part of a complex overall mixed ingredient system in a wide range of food analogs. Such systems are disclosed in, for example, Hawley, U.S. Pat. No. 3,658,550 wherein an artificial adipose tissue is produced by reacting an aqueous solution of an alkali salt of alginic acid and a retarding agent with a fat dispersion of an alkaline earth metal salt to form an alginate gel matrix with the liquid fat entrapped therein in small discrete droplets or globules which are then slowly released by rupture of the walls enclosing the droplets during cooking to baste a simulated analog meat product--i.e., the alginate/meat matrix comprises a honeycomb-like structure containing fat entrapped in the interstices of the honeycomb-like matrix.
Similarly, Feldbrugge et al, U.S. Pat. No. 3,919,435 discloses a meat analog formed from a vegetable protein gel precursor that has incorporated therein animal fatty tissue and/or vegetable oil with a thermostable, polymeric carbohydrate gel. In this disclosure, as in Hawley, supra, fat is employed simply as one ingredient in an overall meat analog system; and, there is no disclosure for, nor intention of, forming integral, discrete, dry, solid, lipid particles or pellets, per se. Algin, in effect, simply forms a barrier between protein and fat fractions in a meat analog containing on the order of only 5% to 30% by weight of fat and/or vegetable oil.
Other similar disclosures are found in: Kofsky et al, U.S. Pat. No. 3,862,336 which discloses an animal food product comprising a dried proteinaceous food substance, an aqueous matrix including a water soluble colloidal binding and gelling agent, and a water soluble, low molecular weight, solid, liquid, or mixture thereof, and which can contain relatively low concentrations of fat; and, Baugher, U.S. Pat. No. 4,098,913 which contemplates the formation of regularly shaped gelled fat particles made by admixing a triglyceride fat or oil and a gelling agent which is then heated and cooled while being agitated to form gelled particles that can be incorporated into meat analogs.
Other patents of general interest include: Strums et al, U.S. Pat. No. 3,991,224 (a whipped food product and process for forming the same); Goryaev et al, U.S. Pat. No. 4,007,248 (a dried fat emulsion concentrate); Schroeder et al, U.S. Pat. No. 4,027,043 (an animal feed supplement in solid, range block form and said to contain fats); British Pat. No. 586,157 (a process for forming simulated fruit and the like from alginates); French Pat. No. 874,977 (an alginate based gel emulsion to form spreadable food analogs); and, French Pat. No. 2,087,852 (an alginate based fruit skin analog and an encapsulated oil-in-water emulsion--i.e., a liquid emulsion within an outer capsule formed of algin--suitable when ruptured for basting meat).
Still other patents of miscellaneous interest pertaining to alginate based compositions and processes for making food products and the like, but which do not contemplate any significant, if any, lipid content, include: U.S. Pat. No. 2,809,893-Poarch et al; U.S. Pat. No. 2,965,498-Hartwig et al; U.S. Pat. No. 2,973,274-Langmaack; U.S. Pat. No. 3,060,032-Glicksman; U.S. Pat. No. 3,362,831-Szezesniak; and, U.S. Pat. No. 3,650,766-Smadar.
In general, it has been found that despite the efforts of a large number of researchers over a prolonged period of time, as exemplified by the foregoing publication and patents, prior to the advent of the present invention no simple, economical system has been developed for delivering a lipid, per se, or high lipid concentration particles, in integral, dry, solid, highly concentrated and stable form to points of use where the lipid can be admixed uniformly in any desired proportion with virtually any type of animal feed product, or where it can be incorporated in otherwise conventional pelletized feed rations containing grain or the like, or where it can be fed to animals by itself, all so as to meet the nutritive requirements of the particular animals in question Indeed, except for the encapsulated protein/lipid/aldehyde disclosures in Scott et al, U.S. Pat. No. 3,925,560 and Rawlings et al, U.S. Pat. No. 4,042,718, neither of which is suitable nor approved for use as an animal feed supplement because the aldehydes employed therein are known carcinogens, none of the prior art approaches have dealt specifically with the need to develop a highly concentrated, integral, solid, dry, lipid pellet per se, enabling lipids to be delivered to a point of use in stable, dry form on a cost-effective basis. Thus, despite all of the foregoing efforts, the "state of-the-art" as it exists at the present time is perhaps best described in the DIRECTOR'S DIGEST, a publication issued by J. D. Schroder, Technical Director, for the Fats And Proteins Research Foundation, Inc. ("FPRF") in Des Plaines, Illinois, the September 1982 issue, No. 152, wherein it is stated:
" . . . Thus far, there have been no breakthroughs in the development of a low-cost, dry fat product. We have followed up on the work that Dr. Boehme did in identifying suitable carriers and have obtained cost figures which will be helpful in considering a product or products to manufacture. PA1 "The number of suitable carriers for fat is quite limited since absorbability characteristics are not the same as for water-based materials such as molasses. To complicate the situation, some products may be suitable for certain markets, while unsuitable for other markets. PA1 "The potential fat carriers, which we have worked with or are familiar with, can be classified as either nutritional or non-nutritional. They are listed below in terms of fat-carrying capacity, price and applicable markets.
______________________________________ F.O.B. FAT PRICE/ CARRYING "INGREDIENT CWT. $ CAPACITY MARKET ______________________________________ Nutritional Puffed rice or $50.00 75-80% All Species wheat Wheat middlings 4.50 30-35% All Species ex- cept broilers Wheat Bran 4.50 40% Cattle & Sows Beet Pulp 6.50 30-40% Cattle Alfalfa Meal $4.00-7.50 30% (est.) All Species ex- cept broilers "Non-Nutritional Verxite $21.00 70% Cattle (expanded mica) Corn cob flour 5.50 50% Cattle & perhaps swine Bentonite 2.50 20% Cattle . . . " ______________________________________
The foregoing FPRF publication goes on to point out many of the disadvantages in terms of transportation costs, low fat content, excessively high costs for higher fat content carriers, and species-specific applications for their use. Thus, despite all of the efforts and expenditures in time and money during the past two decades or more, the present "state-of-the-art" for delivery of lipid food supplements for animals contemplates the impregnation of a host carrier that may or may not have nutritional value and which significantly contributes to the bulk, weight and delivery costs of the feed. And, at the same time, problems of rancidity and difficulty in handling persist.